Storage and retrieval libraries are designed to maximize storage capacity, in terms of the greatest number of media, in the smallest space, or footprint. Previously, the media would be identical and stored in one or more columns or rows of storage cells, and an accessor would move along the column or row to access the media and transport the media between the storage cells and a read/write station.
With the advent of multimedia libraries, the media is no longer identical, and the columns or rows may be of sufficient size to accommodate the largest media. Thus, the storage of small sized media in such a multimedia library wastes a considerable portion of the potential storage space.
An example of a multimedia library which is able to store both multi-sized media is illustrated in coassigned U.S. Pat. No. 5,303,214. As illustrated in the '214 patent, the larger media are approximately twice the width of the smaller media. Thus, in order to save space, the large sized media are arranged in one set of cells in one set of rows, and the small sized media are arranged in another set of cells in another set of rows, and the library is provided with separate picker grippers, a large size picker gripper capable of grasping the large sized media from rows which are wide and therefore widely spaced, and a small size picker gripper capable of grasping the small sized media from rows which are more closely spaced. The variable spacing of the rows requires a costly accessor which can access the variously spaced rows.
The most prevalent storage and retrieval libraries are those which store optical media or which store tape media. In many instances of media used in such libraries, the optical media is larger than the tape media, and typically, the optical media is approximately twice the width of the tape media. In a multimedia library, having optical and tape media, the more common arrangement is therefore likely to have optical media in the library which is twice the width of the tape media in the library.
It would be advantageous to have columns or rows of a common width for storage cells for both optical and tape media and to have a common accessor for accessing both media, the accessor having one picker gripper for accessing the larger (optical) media and another picker gripper on the same accessor for accessing the smaller (tape) media, which would be stored in cells at a common spacing to reduce the cost of the accessor.